docstr: When nodes are disconnected, efficiency is 0
docstr_tok: ["When","nodes","are","disconnected",",","efficiency","is","0"]
code: def test_efficiency_disconnected_nodes(self):
      """
      When nodes are disconnected, efficiency is 0
      """
      assert nx.efficiency(self.G1, 1, 2) == 0
  
file_path: networkx/networkx/algorithms/tests/test_efficiency.py
imports: import networkx
label_desc: Use image node_id 2 for calling the TestEfficiency obj's underlying member method code with example usage: obj.test_efficiency_disconnected_nodes() without return types